Slates -vs- tiles

FreeBear

A timely post over on the Period Property forum....

pip&mims said: Anyway, fast forward to when we purchased as a repossession in 2018, the extension had a patchwork polycarbonate roof which we had recovered in Spanish slate. Almost four years on and these are not holding up well, so I'd definitely not recommend those.

casper_gutman

One thing to be cautious of is that the tiles you posted links to (https://redland.co.uk/products/slate-range/mini-stonewold and https://www.manninghamconcrete.co.uk/quinn-western-slate-tile/ ) are concrete, and seriously heavy - about 50 to 55 kg/m² when installed.

The fibre cement tiles I think of as more typical replacements for natural slates are much lighter, e.g. Cembrit Jutland (https://www.cembrit.co.uk/roofing/fibre-cement-slates/jutland ) are about 20 kg/m².

You need to be very careful before you install something that's significantly heavier than your existing roof covering, or you'll end up with a sagging roof like those you've seen on other houses. Consult a structural engineer if you're uncertain.

theonlywayisup

Down here in North Cornwall we tend to have Delabole slate (Rag slate) - certainly not easy to use and heavier than those you refer to as tiles.  Some on our barn roof are over 1m long. 

Brazilian blue grey and grey green are other favoured slates in Cornwall - which are called "slate tiles".  I like the look of these but like all things in building, they are graded.  Some will literally flake in your hands, the others you could eat your Christmas dinner on.  

What is the loading calculation on your roof timber/truss?  If you are changing the finish then you should work out if the timber/truss supports it. 

JustAnotherSaver

casper_gutman said:

e.g. Cembrit Jutland (https://www.cembrit.co.uk/roofing/fibre-cement-slates/jutland) are about 20 kg/m².

The page/link is not available any more. Strange as I doubt it's gone in such a short time.

I'll have to check in but I'm fairly sure she's been told Spanish slate which doesn't sound good & probably explains the low price.

These that you call fibre cement tiles. I'm wondering if they're what we refer to as fake-slate. I forget the actual name that we see on the tickets. We don't sell or stock many of these though. Their appearance is very very smooth and kind of slate like but you can tell they're quite clearly not slate. They look very uniform. Absolute zero variation in them whereas normal slate can have lumps and bumps and grooves etc.

Thanks for the tips on the weight too. Having suffered my own issues with tradesmen left to do what they think is correct, I don't want her to just let them crack on willy-nilly if what they're doing is either wrong or not going to last 5 minutes beyond payment.

Doozergirl

There's different textures of fibre cement tile, but yes it's probably what you call fake slate.  

https://www.cedral.world/en-gb/roofing/fibre-cement-slates/

It'll last longer than I will, that's for sure.  

stuart45

The problem with Spanish slate is that there's a lot of quarries and quality varies a fair bit between them. As it's only the last 40 years or so they've been used in the UK they haven't been fully tested here yet.
A really good supplier should be aware of which quarries the slates come from.
Canadian slates are a decent quality option. 

casper_gutman

JustAnotherSaver said:

casper_gutman said:

e.g. Cembrit Jutland (https://www.cembrit.co.uk/roofing/fibre-cement-slates/jutland) are about 20 kg/m².

The page/link is not available any more. Strange as I doubt it's gone in such a short time.

...

These that you call fibre cement tiles. I'm wondering if they're what we refer to as fake-slate. ... Their appearance is very very smooth and kind of slate like but you can tell they're quite clearly not slate. They look very uniform. ...

Yes, "fake slate" is about right. Some have a very smooth, uniform finish as you say. Others are textured to give a more realistic riven texture effect, and look closer to slate, e.g. these from the same manufacturer as the above: https://www.cembrit.co.uk/roofing/fibre-cement-slates/westerland

I've fixed the link, by the way - the closing brackets were causing a problem.

JustAnotherSaver

Doozergirl said:

There's different textures of fibre cement tile, but yes it's probably what you call fake slate.  

https://www.cedral.world/en-gb/roofing/fibre-cement-slates/

It'll last longer than I will, that's for sure.  

Ahhh, thrustone, that name rings a bell. I think it was that that I've seen them referred to as.

daveyjp

stuart45 said:

The problem with Spanish slate is that there's a lot of quarries and quality varies a fair bit between them. As it's only the last 40 years or so they've been used in the UK they haven't been fully tested here yet.
A really good supplier should be aware of which quarries the slates come from.
Canadian slates are a decent quality option. 

I know of Spanish slate roofs on UK buildings from 1993 and 1995 which needed major renewal just 10 years later as the slates were crumbling.

stuart45

Some of the Spanish quarries produce soft slates and containing a lot of iron pyrites, although there are others that are reasonable  quality. Welsh slates are still better having been in the ground a couple of hundred million years longer.